Li-ion battery and battery active components on metal wire

ABSTRACT

A battery on a conductive metal wire and components of a battery on a conductive metal wire of circular cross section diameter of 5-500 micrometers and methods of making the battery and battery components are disclosed. In one embodiment, the battery features a porous anode or cathode layer which assist with ion exchange in batteries. Methods of forming the porous anode or cathode layer include deposition of an inert gas or hydrogen enriched carbon or silicon layer on a heated metal wire followed by annealing of the inert gas or hydrogen enriched carbon silicon layer. Energy storage devices having bundles of batteries on wires are also disclosed as are other energy storage devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of pending U.S. patent application Ser. No.13/708,137 filed Dec. 7, 2012, which claims the benefit of priority fromU.S. Provisional Application No. 61/569,228 filed on Dec. 10, 2011, U.S.Provisional Application No. 61/587,632 filed on Jan. 17, 2012, and U.S.Provisional Application No. 61/587,659 filed on Jan. 18, 2012, all ofwhich are hereby incorporated by reference.

FIELD OF THE INVENTION

The invention pertains in general to batteries and, in particular, torechargeable batteries and rechargeable battery components, principallyelectrodes, and methods for making fail-safe damage tolerantrechargeable batteries and rechargeable battery components.

BACKGROUND

The demand for efficiency improvements in energy storage systems isdriving the development of batteries with higher energy density,increased depth of discharge, a longer cycle life and a lighter,flexible form factors. Most current research effort is directed towardsLi-ion batteries (LIBs) because of their inherent higher energy densitycompared to other types of rechargeable battery chemistries, andnegligible memory effect after numerous charge-discharge cycles. Thus,for the past twenty years, significant resources have been directed onimproving electrochemical performance of the active electrode materials,developing safer electrodes and electrolytes, and lowering themanufacturing cost of LIBs. However, LIBs are designed to meet specificapplication requirements and a tradeoff is often made between variousparameters such as high energy density vs. high power, charge-dischargerate vs. capacity and cycle life, safety vs. cost etc. These tradeoffsbecome necessary, primarily due to the limitations imposed by theelectrochemical properties of the active materials, electrolyte, andseparator as well as battery manufacturing methods.

Lithium ion batteries (LIBs) in various shape and size are widely usedin various kinds of portable electronic devices, medical devices and arebeing considered for use in electric vehicle as well for use in solarpower systems, smart electricity grids and electric tools. However,current state of the art (SOA) Li-ion battery technology is limited interms of energy capacity, charging speed and manufacturing cost. Basedon Department of Energy (DOE) reports, ten years of effort, and billionsin spending on Li-ion battery development, the manufacturing cost ofLIBs has not decreased significantly and is still three to six timeshigher than the DOE target ($700/kWh-current vs. $150/kWh-target). Also,performance of Li-ion battery has not improved as expected especiallyfor scalable manufacturing platforms. A key contributor to the pricestagnation and performance plateau is continued reliance on the sametraditional battery manufacturing technology using roll-to-roll foillamination that was developed over 20 years ago. Another contributingfactor is the synthesis of the powder based active electrode materialwhich constitutes 40-50% of the battery cost. Thus, a new battery designand manufacturing paradigm is required to address cost issues. Also, thestate of art graphite anode based Li-ion battery technology is limitedin terms of energy capacity, charging speed and safety. Because oflimited anode capacity, batteries require charging more often.Competitive anode solutions have not overcome fundamental challengesresulting in limited calendar life as well as slow charging.

It has been reported that annealing of the cathode material on asubstrate under proper conditions improves battery performance, aselevated temperature annealing causes the cathode material tocrystallize. However, elevated temperature annealing increases the costof cathode manufacturing. Thus, what is needed is to provide, forexample, a low cost cathode manufacturing method having desired crystalstructure for improved performance and safety.

Lithium-ion batteries are inherently not safe due to foil basedstructure where a large amount of energy is stored. Damage to thebattery can lead to a short circuit releasing large amounts of energyand resulting in thermal runaway, fire, and explosion.

Thus, next generation Li-ion batteries require, for example, a costeffective continuous manufacturing method for battery and batterycomponent as well as, for example, a higher capacity anode solution withfail-safe battery design.

DESCRIPTION OF RELATED ART

Cable type batteries are known in the art addressing need for flexibleform factors. For example, Korean Patent Publication No. 10-2005-0099903to Ahn et al. discloses a thread-type battery having an inner electrodeformed on an inner current collector, an electrolyte formed on the innerelectrode, an outer electrode formed on the inner electrode, and anouter current collector and protective coating part is formed on theouter electrode. U.S. Patent Publication No. 2012/0100408 to Kwon et al.also discloses a cable-type secondary battery including an electrodeassembly which has a first polarity current collector having a long andthin wire shape with a circular cross-section, at least two firstpolarity electrode active material layers formed on the first polaritycurrent collector, an electrolyte layer filled to surround the firstpolarity electrode active material layers, at least two second polarityactive materials formed on the electrolyte layer, and a second polaritycurrent collector configured to surround the outer surfaces of thesecond polarity electrode active material layers. U.S. PatentPublication No. 2012/0009331 to Kwan et al. discloses a method formanufacturing a cable-type secondary battery including use of anelectrode slurry. Among the disadvantages of these batteries and batterycomponents is that they fail to provide a small scale battery with anenlarged area for ion exchange.

SUMMARY OF THE INVENTION

Embodiments of the present invention include a battery component thatuses a long circular cross-sectional metal wire as a substrate for anelectrode in a solid state battery. Thin films on the wire can form acathode, anode, and electrolyte. We define such a battery as energy wireand the embodiments result in battery structures that, for example,combine excellent performance characteristics of a solid state battery(excellent cycle and calendar life, high depth of discharge, rapidcharging rate) with the high energy capacity of a traditional batteryfabricated using powder based active materials. The metal wire substratecan perform as a current collector in an electrochemical cell. Oneembodiment of the invention includes, for example, a low cost method ofmanufacturing an amorphous three dimensional porous silicon-carboncomposite anode active material. One embodiment describes a method wherea porous anode structure is created. In an embodiment, an innovative lowcost annealing technique to heat treat the deposited cathode material isprovided to create desired crystalline as well as porosity of structure.Description of fabricating a high density battery is provided allowingformation of a damage tolerant battery. Further understanding of thenature and advantages of the embodiments of the present invention may berealized by reference to the latter portions of the specification andattached drawings.

In one embodiment, the invention comprises a battery having a conductivemetal wire substrate for first and second porous layers formed on themetal wire, the metal wire, and first and second layers forming a firstcylindrical electrode, a cylindrical second electrode spaced apart fromthe first electrode and an electrolyte disposed between the first andsecond electrode. The porous layers provide an enlarged area for ionexchange between the first and second electrodes.

In one embodiment, the invention comprises methods of making porouselectrode assemblies.

In another embodiment, the invention comprises an electrochemicalapparatus for use in a battery comprising an electrochemical assemblyhaving a conductive metal wire with a circular cross section and aporous electrode layer disposed on the metal wire. The electrochemicalapparatus may form an anode or a cathode. It may be connected to one ormore additional electrochemical apparatuses in parallel or series. Oneform of connection is, for example, weaving together of members ofadjacent electrochemical apparatuses. The electrochemical apparatus maybe used to form different types of batteries.

One embodiment of the invention comprises an energy storage devicehaving an array of batteries, each battery having first and secondcylindrical electrodes formed on a metal wire, with all first electrodesconnected at a first output electrode and all second electrodesconnected at a second electrode output.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a metal wire substrate.

FIG. 2 is a front view of a system for processing a metal wiresubstrate.

FIG. 3a is a cross sectional side view of an embodiment of an anodecomponent.

FIG. 3b is a cross sectional side view of another embodiment of an anodecomponent.

FIG. 3c is a cross-sectional side view of another embodiment of an anodecomponent.

FIG. 4a is a perspective view of plurality of metal wire substrateshaving covers passing through a deposition chamber.

FIG. 4b is a partial cross sectional front view of of metal wiresubstrate of FIG. 4 a.

FIG. 4c is a partial cross sectional side view of the metal wiresubstrate of FIG. 4 b.

FIG. 5a is a cross sectional side view of an anode component.

FIG. 5b is a partial cross sectional view of the anode component of FIG.5a taken along the lines A-A.

FIG. 6 is a front view of an annealing system for a cathode component.

FIG. 7a is a cross sectional side view of a non porous cathodecomponent.

FIG. 7b is a partial cross sectional view of the cathode component ofFIG. 7a taken along the lines A-A.

FIG. 7c is a cross sectional side view of a porous cathode component.

FIG. 7d is a partial cross sectional view of the cathode component ofFIG. 7c taken along the lines B-B.

FIG. 8a is a cross sectional side view of a battery featuring an anodelayer formed on a wire substrate.

FIG. 8b is a cross sectional front view of the battery of FIG. 8a takenalong the lines A-A and a block diagram of circuitry.

FIG. 8c is a cross sectional side view of a battery featuring a cathodelayer formed on a wire substrate.

FIG. 8d is a cross sectional front view of the battery of FIG. 8c takenalong the lines A-A and a block diagram of circuitry.

FIG. 8e is a front view of a battery featuring anode components and afoil based cathode.

FIG. 8f is a front view of a battery featuring cathode components and afoil based anode.

FIG. 9a is a perspective view of a battery assembly of a battery bundleand a block diagram of circuitry.

FIG. 9b is a partial cross sectional view of the battery bundle of FIG.9 a.

FIG. 9c is a magnified view of portion A of FIG. 9 b.

FIG. 9d is a perspective view and partial cutaway view of an energystorage device.

FIG. 9e is a block diagram of circuitry of the energy storage device ofFIG. 9 d.

FIG. 10 is a block circuitry diagram for battery bundles.

FIG. 11a is a cross sectional view of a battery formed with a mandrel.

FIG. 11b is a cross sectional view of the battery of FIG. 11a withoutthe mandrel.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention relates to the manufacturing of asolid state Li-ion battery on a conductive metal wire substrate, withdiverse materials for the cathode, anode, electrolyte and currentcollector, all associated with the wire. FIG. 1 depicts a circularcross-sectional area of metal wire substrate 1. The metal wire 1 worksas a current collector with a diameter D, having a range from 5 micronto 500 micron. Prior to deposition, metal wire can be clean as well astextured to a desired surface roughness using mechanical methods such asbead blasting or chemical methods such as a chemical etching method inorder to enhance mechanical and chemical bonding between electrodecoating and substrate. Having electrodes with circular cross-section,provides an increase in surface area compared to flat rectangular metalsheet or foil electrodes in traditional electrode fabrication. Anincrease in surface area coupled with an decrease in anode filmthickness provides a fast charging capability for LIBs, as a reductionin weight and volume for equivalent energy density. This novel approachto fabricating solid state batteries on a metal wire enables the designof damage tolerant high density batteries.

Fabrication of Anode Material

Embodiments of this invention include a method of low cost manufacturingof a silicon-carbon layered composite anode material using thermalchemical vapor deposition (CVD) technology on a long, circularcross-sectional solid or hollow metal wire made of titanium, steel, ortungsten or tin plated cooper. The most promising means of improving theenergy density of today's lithium-ion batteries is to replace thegraphite based anode with higher energy density material such assilicon. However, the cycling performance of silicon is oftenproblematic due to the large expansion and shrinkage during insertionand extraction of large amounts of lithium. Embodiments of thisinvention addresses several key issues necessary in obtaining superiorLi insertion/extraction performance while maintaining structureintegrity. Further, the capacity of a thin silicon film is not enoughfor practical purposes. An embodiment of the present invention addressesthis by creating a multi-layer silicon and carbon structure where thecarbon layer serves as both an intercalation compound as well as amechanically compliant layer for management of lithiation inducedinternal stresses in addition to creating a reaction barrier between thesilicon layer and the electrolyte, a porous and/or nano-crystallinemicrostructure, excellent substrate—film adhesion, and controlled stressstate within the film structure. The capacity of the silicon-carbonlayered composite anode can be tailored by changing thicknesses ofindividual silicon and carbon layer. The invention of fabricating an“anode-on-wire” structure addresses several key factors necessary inobtaining superior Li insertion/extraction performance. An appropriateanalogy for the anode-on-wire structure is a cylindrical pressurevessel. Using this comparison, stresses in the anode-on-wire structurearising from electrochemical lithiation in thin film are analogous tostresses in a pressure vessel due to combined pressure loading. Siliconexpansion and contraction can be likened to internal and externalpressure loading, respectively, resulting in a primary tangential orhoop stress component. The continuous nature of the hoop stress aroundthe circumference of the cylindrical structure is expected to eliminatethe edge effects and stress concentrations common in planar anodestructures i.e., lower compressive stress level in the film stack forthe circular cross-section geometry as compared to the planar geometry.The use of a circular cross-section wire for anode fabrication providesseveral key benefits as compared to a traditional flat plate anodestructure including accommodating volume expansion related stresses.

Application of thermal CVD to deposit structural ceramic film on varioussubstrate forms is a well known process. However, the prior art methoddoes not serve the needs of this invention in which, for example, amulti-layer thin film porous structure is formed as an electrochemicalactive material. In an embodiment of this invention a multistage reactor20 (FIG. 2) is designed to create such an electrochemical activematerial as described below.

In one embodiment of the invention, the wire 1 (FIG. 1) is resistivelyheated while carbon and/or silicon containing precursors are introducedat various locations to deposit anode material on the circumference ofthe metal wire 1. Traditional CVD precursors for silicon (such asdicholorosilane) and for carbon (such as methane) are introduced alongthe length of the reactor 200 (FIG. 2). Decomposition of the precursorcompound is achieved by a thermal breakdown mechanism when precursorcontacts the heated wire surface. External plasma sources such as RF orMicrowave can also be used to further assist the decomposition rate ofactive precursor material. Amorphous and/or nano-crystallinesilicon-carbon layered composite anode material is deposited on movingwire with thicknesses ranging from 2 to 20 μm depending upon thedeposition parameters. The speed of the moving wire can be varied toincrease or decrease the thickness of deposited anode material.Deposition temperature can be varied by resistively heating the metalwire with different current densities while it is moving through thedeposition chamber. The deposition temperature of the moving wire indifferent chambers of the reactor 20 can be adjusted by introducingappropriate amount of cooling gas such hydrogen or helium. Variation inthickness of the individual coating layers can also be achieved byvarying the ratio of chemistry to dilution gas, such as hydrogen orargon, within the process chamber. Following is an example method of atypical process sequence envisioned for fabricating “anode-on-wire”structures:

-   1. Resistively heating of wire and hydrogen etching of native oxide    in chamber 202.-   2. Deposition of a silicon adhesion layer (˜20 to 50 nm thick) in    chamber 204.-   3. Deposition of the first carbon coating as a stress compliant    layer in chamber 206.-   4. Deposition of the silicon layer in chamber 208.-   5. Deposition of a second carbon coating as a stress compliant layer    in chamber 210.    The described manufacturing method is applicable for other suitable    anode material for a Li-ion battery.

FIG. 2 depicts a metal wire 2 continuously moving through the depositionchambers, for example chambers 202, 204, 206, 208 and 210, in a chemicalvapor deposition reactor 200. Tensioners may be used to control tensionof the wire and the wire feed collected on reels 214 and 218. In oneembodiment amorphous or nano-crystalline carbon-silicon-carbon thickfilm composite anode is deposited using high vapor pressure precursorsfor carbon and silicon. In order to deposit anode material on thecircumference of the metal wire, wire is resistively heated while carbonand/or silicon containing gases are introduced at various locations. Forcarbon constituent of the anode, CVD gasses such as Methane or Acetyleneor hexane or any carbon atom containing precursor gas with vaporpressure greater than 0.5 torr can be used. Carbon containing liquidprecursor such as dimethyl adamantane can also be used in conjunctionwith a liquid evaporator and mass flow controller. For siliconconstituent of the anode, CVD gasses such as mono silane or any variantof silicon containing gas (or high vapor pressure liquid) is used. Gasescontaining both carbon and silicon constituent such as methyl silane canalso be used to form carbon-silicon thick film composite anode.Deposition temperature ranges from 200 to 2000 degree Celcius and areachieved by resistively heating the metal wire while it is movingthrough the deposition chamber. Exhaust gasses are pumped through portsor outlets 222, 226, 230, 234 and 238.

Referring to FIG. 2, anode material is deposited on the circumference ofthe metal wire 2 as the wire is resistively heated. Brush basedelectrical connection points 240 and 242 provide current for resistiveheating. H₂ gas is introduced into chamber 202 through inlet 220 forhydrogen etching of wire 2. Exhaust gas is pumped out outlet 222.Silicon precursor is introduced into chamber 204 through inlet 224 fordeposition of a silicon adhesion layer on the wire 2. Exhaust gas ispumped out outlet 226. Carbon precursor is introduced into chamber 206through inlet 228 for deposition of a first carbon coating as a stresscompliant layer on the silicon adhesion layer. Exhaust gas is pumped outoutlet 230. Silicon precursor is introduced into chamber 208 throughinlet 232 for deposition of a silicon layer on the carbon layer. Exhaustgas is pumped out outlet 234. Carbon precursor is introduced intochamber 210 through inlet 236 for deposition of a carbon layer on thesilicon layer. Exhaust gases are pumped out of outlet 238.

In another embodiment, as depicted in FIG. 3a , a carbon layer 10,thicker than 10 nm but thinner than 5 microns, is deposited on metalwire current collector 12 followed by deposition of silicon layer 14 ofvarious thicknesses ranging from 1 micron to 100 microns. In anotherembodiment as depicted in FIG. 3b , a thin silicon layer 16, thickerthan 10 nm but thinner than 5 microns, is deposited followed by a carbonlayer 18 with thicknesses ranging from 1 micron to 100 microns. Asdepicted in FIG. 3c , alternate layers of carbon 20 and silicon 22 aredeposited with thickness ranging from 10 nm to 100 microns. Based onthese embodiments, various other configurations of silicon and carbonlayers are possible such as the deposition of a single layer of siliconor a single layer of carbon on a metal wire as described above.

FIG. 4a illustrates a metal wire 12 moving through the depositionchamber 32 guided into the chamber by guide rollers 33. Before the metalwire substrate enters the deposition chamber 32, a cover 34 is placedover the metal wire at desired locations along the length of the wire toprevent deposition at selected areas along the length of a metal wire 12moving through the deposition chamber 32. The distance between coverplacement 36 (FIG. 4b ) along the length of metal wire substrate canvary depending upon the size of anode wire (FIG. 4c ) that is needed fora particular application. This cover can be made of ceramic or metalsheet. Once the deposition is complete and at the exit end of thedeposition chamber, the cover 34 can be removed exposing the metal wireunderneath. These uncoated areas can be used for electrical connectionin an electrochemical cell.

In one embodiment the moving wire is resistively heated while siliconand/or carbon containing precursor gasses are introduced at locationsalong with diluting gases such as hydrogen or inert gas. In one example,a hydrogen enriched silicon layer includes 10-80% hydrogen. In anotherexample, an argon enriched carbon layer includes 10-80% argon. Processconditions such as pressure, temperature, flow rates and precursor gasesto diluting gases ratio are varied so that hydrogen and/or inert gas istrapped within the growing anode layers. After the formation of theanode layers, the anode coated wire is passed through a vacuum chamberwhile heated resistively above 1000 degree Celsius. This causes trappedhydrogen and/or inert gas within the anode layers to escape creatingdiffusion paths and a porous structure. This method can be applied tocreate porous cathode structure resulting in more rapidcharging/discharging of battery. This structure is shown in FIGS. 5a and5b , with metal wire 12 anode coating 42 and pores 44. The followingsteps are an example method used to create such structure.

-   1. Resistively heating of wire and hydrogen etching of native oxide.-   2. Deposition of a silicon adhesion layer.-   3. Deposition of a highly argon enriched carbon layer by increasing    the argon to carbon precursor ratio.-   4. Subsequent vacuum annealing of wire and argon enriched carbon    layer allowing escape of argon gas from the carbon layer, creating    porous pathways within the carbon layer.-   5. Deposition of a highly hydrogen enriched silicon layer by    increasing the hydrogen to silicon precursor ratio.-   6. Subsequent vacuum annealing of the hydrogen enriched silicon    layer and wire allowing escape of hydrogen from the silicon layer,    creating a porous silicon layer structure.-   7. Deposition of a carbon coating as a stress compliant layer as    well as reaction barrier between silicon and electrolyte.    Fabrication of Cathode Material

Embodiments of the present invention relate to method of manufacturing acathode active material on a long circular cross-sectional metal wiresubstrate. This metal wire substrate performs as current collector in anelectrochemical cell. In an embodiment, the cathode material (such asLiCoO2) is deposited on a metal wire employing a method similar to anodeformation as described above but with using cathode forming precursors,physical vapor deposition, thermal spray, spray pyrolysis, sol gel andapplicable powder metallurgy method using cathode material and/orcathode material precursor with or without binding material. Liquidphase deposition could also be used. This low cost manufacturing methodis applicable for layered, spinel, and olivine type structures as wellas metal alloy based cathode materials suitable for Li-ion typebatteries. In an embodiment, cathode material is deposited on a metalwire substrate resistively heated at temperatures ranging from 100degree Celsius to 2000 degree Celsius. As the coefficient of thermalexpansion of metal wire substrate is higher than the cathode material,strain is introduced within the cathode material and higher level ofstrain induced crystallization is achieved.

In an embodiment, an innovative low cost annealing technique to heattreat the deposited cathode material is provided. After deposition ofthe cathode material on the metal wire substrate, in a sequential step,an electric current is passed through the metal substrate forresistively heating the substrate to desired temperature to inducedesired diffusion, crystallization and bonding within deposited cathodematerial. FIG. 6 is a schematic of a device for a low cost elevatedtemperature annealing method for deposited cathode. A continuousas-deposited cathode metal wire 50 is passed through an annealingchamber 52 from a wire reel 54 to a receiving reel 56. An electriccurrent is passed through the metal wire by power supply 60 usinguncoated area (FIG. 4) at connection points 58 heating the metal wireresistively. Temperature can be monitored using sensor 62 and controlledby feedback to the power supply 60. Set-point electrical current canalso be applied thru the deposited material. The temperature of thecoated metal wire can be controlled by varying the input current forresistance heating and ranges from 200 C to 2000 C. Various environmentssuch as oxygen or nitrogen or fluorine can be introduced during theannealing process.

FIGS. 7a and 7b are cross-sectional longitudinal and side views ofannealed cathode material 70 on a wire substrate 12. The degree ofcrystallization is controlled by varying the temperature and time withan increase in temperature and/or time resulting in an increase incrystal size.

In one embodiment, prior to cathode deposition, wire is resistivelyheated while silicon and/or carbon containing gasses are introduced inthe chemical vapor deposition reactor 200 (FIG. 2) along with hydrogenor inert gas such as argon for anode formation as described above.Process conditions are varied so that hydrogen and/or inert gas gettrapped within the growing porosity forming coating. This is followed bydeposition of cathode material as per the teachings described above.During cathode annealing, trapped gases within the carbon or siliconlayer escape creating a porous cathode structure. FIGS. 7c and 7d depictannealed cathode 74 with porous structures 76 and a thin base carbonlayer 80 deposited on wire substrate 12. In one example, the carbonlayer is thinner than 5 micrometers and is deposited as described abovefor anode formation in FIG. 5 before deposition of cathode material.Further understanding of the nature and advantages of the presentinvention may be realized by reference to the latter portions of thespecification and attached drawings.

Fabrication of Solid State Battery

According to the teachings described in this disclosure for thefabrication of anode and cathode, a solid state battery can bemanufactured where an electrochemical cell structure will be created onan integral high surface area metal wire substrate with circular crosssection. An advantage of embodiments of this invention are that, forexample, they result in a battery structure that combines excellentperformance characteristics of a solid state battery (excellent cycleand calendar life, high Depth of Discharge, rapid charging rate) withthe high energy capacity of a traditional battery fabricated usingpowder based active materials.

This low cost continuous manufacturing technology may be used to createa three dimensional array of high capacity, porous film based“battery-on-wire” structures. Individual “batteries-on-wire” ofdifferent diameters are bundled to improve packing density and connectedin series or parallel, as required by the application, to form a highcapacity battery. The bundled “battery-on-wire” can be as long asrequired by application changing the length of individual wire.

The “battery-on-wire” technology has the potential to create a LIB withextremely high charge-discharge rate with sufficient energy density andcycle life. Embodiments of this invention may accomplish highcharge-discharge rate by reducing the path length over which theelectrons and Li ions move by the use of a multilayer porous filmstructure coupled with large surface area and increased anode capacitybased on silicon. Embodiments of this invention may achieve highspecific energy density of the “battery-on-wire” structure by combiningwire geometry with a high capacity three dimensional porous siliconcontaining anode and a less than 2 micron thick electrolyte layer,resulting in a significant improvement in both volumetric andgravimetric capacities.

Referring to FIG. 8a , in one embodiment of the present invention amethod of manufacture of a solid state Li-ion battery (80) comprises thefollowing steps: (1) depositing an active anode material 82 on a metalwire 12 as described in above teaching, (2) depositing a lithiumphosphorous oxy nitride (LIPON) or other suitable electrolyte 84 usingstandard deposition techniques or as described in above teaching foranode fabrication using appropriate electrolyte precursors (3)depositing an active cathode material 86 as described in above teaching,4) elevated thermal annealing of deposited cathode material to inducedesired level of crystallization in selected environments as describedabove, and 5) metal current collector electrode 88 deposition usingprecursors of conductive metals such as Al, Cu, or W by an establishedmethod such as plasma spray or physical vapor deposition or sputtering.

In another embodiment as referred in FIG. 8c , solid state LIBs 90 aremanufactured by: 1) depositing an active cathode material 92 on a metalwire 12 as described in above teaching, (2) a elevated thermal annealingof deposited cathode material 12 to induce desired level ofcrystallization in selected environments as described above, (3)depositing a lithium salt such as lithium phosphorous oxy nitride(LIPON) or other suitable electrolyte 94 using standard depositiontechnique or as described in the above teaching for anode fabricationusing appropriate electrolyte precursors, (4) depositing an active anodematerial 96 as described in above teachings and (5) metal currentcollector 98 deposition using precursor of conductive metals such as Al,Cu, or W by an established deposition method such as plasma spray orphysical vapor or sputtering. A power source is indicated by the letterP.

In one embodiment as referred in FIG. 8e , an LIB 101 is shown comprisedof: an anode on metal wire 100 fabricated with the teachings describeabove with liquid electrolyte 102 such as LiPF6 and traditional foilbased cathode 104 such as LiCoO2 on copper foil with a separator 106.Anode on metal wire can be of various geometrical forms such as woven,cross-weave, hollow spiral, multiple stacks etc. The anode on wireconfiguration provides tremendous geometric and functional capability tothe manufacturing technique.

In another battery (110) embodiment as referred in FIG. 8f , cathode onmetal wire 112 fabricated with the teachings describe above is used withliquid electrolyte 114 such as LiPF6 and traditional foil based anode116 such as graphite on aluminum foil with a separator 118. Cathode onmetal wire 112 can be of various geometrical forms such as woven,cross-weave, hollow spiral, multiple stacks etc. The cathode on wireconfiguration provides tremendous geometric and functional capability tothe manufacturing technique.

In another embodiment, both anode and cathode on separate metal wiresfabricated with the teachings describe above can be used with a liquidelectrolyte such as LiPF6 or polymeric electrolyte along with aseparator to fabricate a lithium ion battery. Both anode and cathode onmetal wire can be of various geometrical forms such as woven,cross-weave, hollow spiral, multiple stacks etc. The active componentformation on wire configuration provides tremendous geometric andfunctional capability to the manufacturing technique. Also, magneticfield induced due to flow of current through the metal wire substratecan be harvested by arranging metal wire battery parallel, series orcross weave pattern to enhance internal potential of electrochemicalcell.

Exemplary configurations described herein are for illustration purposesonly and they do not intend to limit the full scope of the possibleconfigurations and combinations that can be achieved following theprinciples of the present disclosure. The principles of these teachingscan be applied for individual components such as the electrodes orelectrolytes or any combination thereof.

Fail-safe and Damage Tolerant Battery Design

Embodiments of this invention facilitates implementation of controlcircuitry for charging and safety at both the single as well as themultiple bundle level allowing fabrication of a damage tolerant andinherently safe battery structure. Existing foil-based cells requireexternal protection circuitry to prevent thermal runaway and/or cellrupture in the event of anode-cathode shorting. These externalprotection circuits reduce the volumetric efficiency of a given cell andoften require parasitic current draw from the cell which is beingprotected. The proposed “battery-on-wire” cell structure can act as anintegrated protection circuit, based on the principle of a thermalswitch. The current carrying capacity of the “battery-on-wire” will bedesigned by selecting appropriate wire diameter such that the wire willmelt at predesigned location and open the circuit in the event ofanode-cathode shorting, effectively making each individual“battery-on-wire” in the bundle a thermal switch. As compared toexisting foil-based cells, the “battery-on-wire” structure is expectedto provide superior safety, improved volumetric efficiency and requireno parasitic current draw for maintenance of an external protectioncircuit.

In one embodiment as referred in FIGS. 9a -9 e, arrays or bundles 900 ofmultiple low energy density wire batteries 901 with different diameterto improve packing density are bundled together to form a high densitybattery 902 suitable for electronics, vehicle, medical, defense andenergy storage applications. Referring to FIGS. 9a -9 c, each battery901 of the bundle 900 includes a conductive metal wire substrate 904, ananode material layer 906 deposited on the metal wire substrate spacedapart from a cathode material layer 910, an electrolyte 908 disposed inthe space between the anode material layer and the cathode layer and atop current collector 912. The diameter of the metal wire 904 within thebundle 900 ranges from 2-500 micron and is selected appropriately toimprove packing density within the bundle. FIG. 9a depicts a singlebundle 900 of an array of batteries-on-wires connected in parallel. Thebundle includes a polymer casing 903. Depending upon the applicationrequirements diameter and length of individual wire as well as number ofthe wire in a bundle can be changed.

Referring to FIGS. 9d and 9e , the high density battery 902 may bepackaged in a polymer sheath 914. Anode terminal 904, anode connectionwires 906 and cathode connection is shown to form the monolithic battery902. Single wire batteries 901 can be connected in parallel as requiredby the application. These bundled wire batteries can be as long asrequired limited by the length of an individual wire battery.

In bundle 900, outermost or top current collectors 912 (FIG. 9e ) foreach energy wire 901 are touching each other and electrons are harvestedat multiple locations along the length of energy wires. Top currentcollectors 912 are made of conductive metal including for example steel,tungsten, or coated metals, or ceramic wire. Hundreds of single batterywires can be connected in parallel to form one battery bundle 900.Depending upon the current requirements, the number and length of wirecan be increased as required by application while appropriate singlebattery wire diameter can be selected to improve packing density ofsingle bundle. For example, an individual battery 901 may have adiameter greater than 50 micrometers and may be up to 10 miles long.Further, several bundles 900 can be connected in series to generate therequired application voltage. Several bundles depicted in FIG. 9e areconnected in series to make a higher capacity battery. Depending uponthe application requirements the number of bundles in a battery can beincreased.

This concept facilitates implementation of control circuitry forcharging and safety at both, the single as well as the multiple bundlelevel. Isolation of the metal cores from the bundled ends is required inthe end region of each group to prevent local shorting of the anode andcathode for a robust battery. This is achieved by placing a cover orspacer over the metal wire before wire enters the deposition chamber asdescribed in FIGS. 4a and 4b . Exemplary configurations described hereinare for illustration purposes only and they do not intend to limit thefull scope of the possible configurations and combinations that can beachieved following the principles of the present disclosure.

According to the teaching set forth in this disclosure and referred toin FIG. 10, damage tolerant battery design embodiments are described. Asrequired by the application, bundles 1000 a-e of single energy wire areconnected in series by series connection 142 to form a high energydensity battery 1002 connected, for example, to a power source 132. Asdepicted in FIG. 10, fabrication of a high energy density battery, asdescribed, including multiple low energy wire battery allows damage 134to the battery 1002 where only the damaged wire batteries 1000 a and1000 c become non-functional while other bundle wire battery 1000 b,1000 d, and 1000 e perform although with lower energy output. Theapplication of this invention prevents release of large amount of energydue to shorting between anode and cathode within energy wire bundle.Anode-cathode shorting due to damage releases low energy only from thedamage single wire battery bundle as compared to foil based design wherelarge amounts of energy can be released.

Embodiments of the present invention also offer a high degree offlexibility as compared with conventional approaches and offersignificant advantages as presented in electrochemical cell in FIGS. 11aand 11 b. For example, anode and cathode wire can be used to create aspiral structure. According to the teaching set forth in this disclosureand referred to in FIG. 11 a, an anode wire 151 with integratedseparator 152 is wrapped around a mandrel tube 150 with holes. This isfollowed by wrapping a cathode wire 153 and casing material 154. Anodewire 151 and cathode wire 153 are used as current collector. Both theanode and cathode may be made from, for example, conductive metal,coated metal, metal coated oxide, or carbon wire. Mandrel tube 150 isfilled with standard electrolyte such as LiPF6 to make a spiral wirebattery. These spiral wire batteries can be as long as required limitedby the length of mandrel tube 150. Several other modification of suchapproach is envisioned. In another embodiment as described in FIG. 11 b,hollow mandrel tube 150 is removed after filling with liquid electrolyte157 with casing material 158 providing containment. Such spiralstructure can also be created using solid state battery wire (FIG. 8)with and without mandrel tube 150 using the method described above.Exemplary configurations described herein are for illustration purposesonly and they do not intend to limit the full scope of the possibleconfigurations and combinations that can be achieved following theprinciples of the present disclosure.

The invention claimed is:
 1. A method of forming an electrode assembly comprising: heating a conductive metal wire having a circular cross section and length to diameter aspect ratio larger than 100:1; concentrically nucleating and concentrically growing either an inert gas or hydrogen enriched carbon or silicon layer on the metal wire to form an electrode layer having a circular cross section; and annealing the inert gas or hydrogen enriched carbon or silicon layer and the metal wire current collector, wherein annealing creates pores in the electrode layer, the pores providing an enlarged area for ion exchange in a battery.
 2. The method of claim 1, further comprising concentrically nucleating and concentrically growing a cathode material layer on the inert gas or hydrogen enriched carbon or silicon layer to form a cathode layer before annealing.
 3. The method of claim 1, wherein the electrode layer is an anode layer.
 4. The method of claim 1, wherein annealing comprises vacuum annealing.
 5. The method of claim 1, further comprising hydrogen etching oxide of the metal wire before depositing the inert gas or hydrogen enriched carbon or silicon layer.
 6. The method of claim 1 further comprising resistively heating the conductive metal wire.
 7. The method of claim 1, wherein an argon enriched carbon layer is concentrically nucleated and concentrically grown on the wire and further comprising depositing a hydrogen enriched silicon layer on the enriched carbon layer after annealing the argon enriched carbon layer.
 8. The method of claim 7 further comprising depositing a carbon coating stress compliant layer on the hydrogen enriched silicon layer.
 9. The method of claim 1, wherein a hydrogen enriched silicon layer is concentrically nucleated and concentrically grown on the metal wire and further comprising depositing an argon enriched carbon layer on the hydrogen enriched silicon layer after annealing the hydrogen enriched silicon layer.
 10. The method of claim 1 wherein the inert gas or hydrogen enriched carbon or silicon layer is grown having a percentage of hydrogen ranging from 10% to 80%.
 11. The method of claim 1 wherein the inert gas or hydrogen enriched carbon or silicon layer is grown having a percentage of argon ranging from 10% to 80%.
 12. The method of claim 1 further comprising depositing a silicon adhesion layer before depositing the inert gas or hydrogen enriched carbon or silicon layer.
 13. The method of claim 1 further comprising introducing a desired amount of cooling gas, including hydrogen or helium, into each deposition chamber of a reactor through which the conductive metal wire is moving thereby controlling reactor chamber temperature. 